I'm going to agree with the other ladies here. Hope your girlfriend gets off the crack . . . that is definitely not a sexy habit or a good quality to have in a significant other. good luck
No, you wouldn't test positive that way. If you didn't ingest, inhale, snort, inject, or touch it (crack) directly don't worry about it. The only way people have tested positive for very small amounts (in hair sample tests), who aren't direct users, are people exposed to second-hand smoke over a long period of time...
Just a guess but it doesn't seem likely that you would get any detectable controlled substance in your system from that activity.